Quadrature modulators operate on separate in-phase (I or i) and quadrature (Q or q) data corresponding to a single transmit or receive signal. Modern transmitters, such as direct conversion radio transmitters and quadrature modulators, are driven by digital circuits at very high sampling rates. Even though the in-phase and quadrature data is created digitally in perfect quadrature from the same signal, it is distorted by the analog circuits during transmission due to phase, gain and direct current (dc or DC) errors inherent in such analog circuits. As a result, compensation for these errors must be substantially continuous due to circuit variations over time, temperature and ever widening bandwidths. Therefore, an improved method of compensating for phase, gain and dc errors associated with the analog circuits of analog transmitters would be a significant improvement in the art.